Typical beverage cups with an open top and open rim designed for standard gravity applications lose their functionality when employed in zero gravity or microgravity environments such as those found on spacecraft and space stations. A beverage placed inside such a cup will adhere to the base of the cup interior due to capillary forces. The adherence is maintained regardless of the orientation of the cup, making it impossible for a user to tilt the beverage towards the rim, and thus preventing the user from imbibing in the typical fashion. Further, any inertial forces applied to the cup that are greater than the capillary forces will cause the beverage to dissociate from the cup.
The current, widely accepted method for imbibing liquids in space utilizes completely sealed vesicles, such as a bag. Liquids may be withdrawn from the bag via a user sucking through a straw, or by squeezing the bag by hand, forcing liquid out of the bag and into the mouth of a user. By completely containing the liquids in a sealed vesicle, clean delivery is ensured. However, flavor is reduced, as aromatics are nearly completely eliminated. Further, the experience of sipping or drinking a beverage is lost, and the user may feel unsophisticated by being limited to sucking liquids from a bag. Especially for individuals who spend extended periods of time at a space station, even modest comforts of home may improve their mental health and well-being. For extended missions, it may also prove effective to rely on reusable cups rather than disposable bags.
U.S. Pat. No. 8,074,827 describes one approach for providing an open-topped beverage cup for use in low gravity environments. The beverage cup described therein uses a corner channel to exploit capillary forces and allow a beverage contained therein to be directed to the rim of the cup. However, the design has limitations, as recognized by the inventors herein. For example, the capillary pressure gradient dissipates as the liquid level decreases, thereby making it difficult to completely drain a beverage from the cup in a reasonable amount of time. This problem is aggravated by the fact that no capillary gradient is established along the interior corner to promote a more conducive drinking rate. As another example, the corner channel extends to the rim of the cup, forcing the user to drink from a tapered point, making the experience less like drinking at standard gravity. Further, the stability of the beverage within the cup is limited, reducing the amount of liquid that may be held therein while maintain capillary forces in excess of potential inertial forces.
A capillary beverage cup may be used to provide a liquid for drinking in a low-gravity environment. The capillary beverage cup may comprise an open top, allowing for aromatics to be experienced by a user while drinking. The capillary beverage cup may provide a continuous capillary force on the liquid contained by the cup, utilizing a continuous interior corner extending from a lip interface into an inner cavity of the capillary beverage cup that is activated as fluid is removed from the lip interface. The continuous interior corner may comprise an acute included angle which tapers continuously as the interior corner approaches the lip interface, allowing the cup to provide continuous increased capillary under-pressure (e.g. suction) on liquids with a contact angle less than 70°. The lip interface may comprise a cusp-shaped channel that is continuous with the continuous interior corner and extends to an edge of the lip interface. In this way, a rivulet of liquid may be presented at the lip interface for imbibing, the upper lip providing a capillary connection with the liquid in the cusp and thus the entire liquid contents within the cup. A user may withdraw the liquid by applying a sucking force, or with small quantities of liquid wicked into the mouth without applying a sucking force, but by merely coupling the user's lip to the lip interface of the cup. The capillary beverage cup may include a rounded, low-curvature region assuring that the vessel is completely drained by the continuous interior corner, though the interior corner may not extend into the rounded, low curvature region.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.
Note: Figures are drawn approximately to scale, but other dimensions may be used.